The Babcock & Wilcox Owners Group (B&WOG) Flux Perturbation Experiment in the Oak Ridge National Laboratory Poolside Facility simulated the thermal shield, downcomer, pressure vessel, and cavity region of a B&W-designed 177-fuel assembly reactor by an arrangement of steel slabs and a void box. Two simulated surveillance capsules located in the downcomer were irradiated as part of the NRC-sponsored Light Water Reactor Pressure Vessel Surveillance Dosimetry Improvement Program. The capsules contained extensive dosimetry provided by B&W and the Hanford Engineering Development Laboratory (HEDL). Dosimeters were also located outside of the capsules in the downcomer region. Flux distributions were calculated throughout the test configuration using the two-dimensional DOT 4.3 transport theory code. The calculated and measured data are compared in this paper.